X-cube integrated solid optics component

ABSTRACT

An X-cube integrated solid-optics component which can perform beam-splitting and filtering functions among four input beams. The X-cube component can also be used for various wavelength-division multiplexing communication and interconnection applications, such as star-coupling, wavelength routing, and add/drop multiplexing. The X-cube component comprises an assembly of four right-angle roof-top prisms positioned with the apex of each roof-top prism at the center of the assembly, such that assembly defines two mutually orthogonal and intersecting internal planes which intersect at the center of assembly to form four sections of the intersecting internal planes. The four plane sections form up to four or more primary optical channel paths having up to four or more potential inputs IAI, IBI, ICI, IDI and four or more potential outputs IAO, IBO, ICO, and IDO, and the outputs depend upon functionalities provided by the four sections of the intersecting internal planes.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates generally to an X-cube integrated solidoptics component, and more particularly pertains to an X-cube integratedsolid optics component which comprises an assembly of four right-angleroof-top prisms positioned with the apex of each roof-top prism at thecenter of the assembly. The assembly defines two mutually orthogonal andintersecting internal planes which intersect at the center of assemblyto form four sections of the intersecting internal planes. The fourplane sections form up to four or more primary optical channel pathshaving up to four or more potential inputs I_(AI), I_(BI), I_(CI),I_(DI) and four or more potential outputs I_(AO), I_(BO), I_(CO), andI_(DO), and the outputs depend upon functionalities provided by the foursections of the intersecting internal planes.

Concepts of space-filling solid optics have been introduced in the pastfew years to address packaging concerns of opto-electronic systems [M.P. Schamschula, H. J. Caulfield, and A. Brown, “Space filling modularoptics,” Opt. Lett., 19 (1994) 689-691; M. P. Schamschula, P. Reardon,H. J. Caulfield, C. F. Hester, “Regular geometries for folded opticalmodules,” Appl. Opt. 34 (1995) 816-827; J. Jahns, “Planar packaging offree-space optical interconnection,” Proc. IEEE, 82 (1994) 1623-1631].Instead of having to use separate mountings for various discrete opticalcomponents, solid optics modules integrate these components together toform a single compact unit.

The present invention concerns a new type of solid optics module, anX-cube, for effective beam splitting and optical filtering. Such beamsplitting and filtering functions are becoming integral parts of futurelocal optical interconnections using wavelength-division multiplexing(WDM) techniques. In fact, as technology migrates from 1 Gb/s Ethernetto 10-Gb/s Ethernet environments in the near future, methods forhandling 4×2.5 Gb/s WDM channels are actively being researched [H.Nakano, S. Tsuji, S. Sasaki, K. Uomi, and K. Yamashita, “10-Gb/s,4-channel WDM fiber transmission using semiconductor optical amplifiermodules”, IEEE J. Lightwave Tech., 11 (1993) 612-618]. Four-channelfiber-based optically functional components and devices will become anactive research and development area.

SUMMARY OF THE INVENTION

Accordingly, it is a primary object of the present invention to providean X-cube integrated solid optics component for optical beam splittingand/or optical filtering. The X-cube component comprises an assembly offour right-angle roof-top prisms positioned with the apex of eachroof-top prism at the center of the assembly, such that the assemblydefines two mutually orthogonal and intersecting internal planes whichintersect at the center of assembly, to form four sections of theintersecting internal planes. The four plane sections form up to four ormore primary optical channel paths having up to four or more potentialinputs I_(AI), I_(BI), I_(CI), and I_(DI) and four or more potentialoutputs I_(AO), I_(BO), I_(CO) and I_(DO), and the outputs depend uponfunctionalities provided by the four sections of the intersectinginternal planes.

Denoting intensity transmission coefficients which can be functionallystatic or dynamic with respect to time, of the four sections of theintersecting internal planes as t_(a), t_(b), t_(c), and t_(d) andassuming ideal lossless conditions at the intersecting internal planes,the integrated solid optical module defines the following set ofinput-output relations,

I_(AO)=I_(AI)(1−t_(a))(1−t_(d))+I_(BI)t_(a)(1−t_(d))+I_(CI)t_(c)t_(d)+I_(DI)(1−t_(c))t_(d)

I_(BO)=I_(AI)t_(a)(1−t_(b))+I_(BI)(1−t_(a))(1−t_(b))+I_(cI)(1−t_(c))t_(b)+I_(DI)t_(c)t_(b)

I_(CO)=I_(AI)t_(a)t_(b)+I_(BI)(1−t_(a))t_(b)+I_(CI)(1−t_(c))(1−t_(b))+I_(DI)t_(c)(1−t_(b))

I_(DO)=I_(AI)(1−t_(a))t_(d)+I_(BI)t_(a)t_(d)+I_(CI)t_(c)(1−t_(d))+I_(DI)(1−t_(c))(1−t_(d))

Depending upon the transmission coefficients, the X-cube component andthe four outputs are used for different applications.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing objects and advantages of the present invention for anX-cube integrated solid optics component may be more readily understoodby one skilled in the art with reference being had to the followingdetailed description of several preferred embodiments thereof, taken inconjunction with the accompanying drawings wherein like elements aredesignated by identical reference numerals throughout the several views,and in which:

FIG. 1 is a schematic illustration of a top view of an optical X-cubewherein t_(a), and t_(b), t_(c), t_(d) are intensity transmissioncoefficients for four prism internal interfaces.

FIG. 2 illustrates respectively axial (lateral (b), and angular (c)alignment sensitivity measurements of a collimating-focusing fiber pair,wherein (b) and (c) are obtained for a d=60 mm gap distance.

FIG. 3 illustrates an embodiment which adds additional sets (1 to n)optical channel paths beyond the one set of four primary optical channelpaths, wherein each additional set of four optical channel paths ispositioned at a different fixed and spaced position along the centrallongitudinal axis of the X-cube.

FIG. 4 illustrates a further embodiment which also adds additional sets(1 to n) of optical channel paths, wherein each additional set of fouroptical channel paths is positioned in the same plane perpendicular tothe central axis of the X-cube, but is spaced at a different distancefrom the central axis of the X-cube.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to the drawings in detail, FIG. 1 is a schematic illustrationof an X-cube 10 and a possible function thereof. The X-cube 10 is formedby assembling together a set of four substantially identical right-angleroof-top prisms 12, 14, 16 and 18. The assembled optical cube has twomutually orthogonal and intersecting internal planes which form an X,and thus the cube is termed an X-cube. However it should be notedinitially that although the term X-cube has been chosen because of the Xplane configuration shown in FIG. 1, the assembly is not a true cube asthe dimension in the z direction (out of the drawing) is not equal tothe x and y dimensions.

When the X-cube is used in a way as suggested in FIG. 1, it has fourinputs I_(AI), I_(BI), I_(CI), and I_(DI), as well as four outputsI_(AO), I_(BO), I_(CO), and I_(DO), respectively. Exactly what will begenerated at the outputs depends upon functionalities provided by thefour sections of the X-shaped intersecting planes. Denoting theintensity transmission coefficients of the four sections of these planesas t_(a), t_(b), t_(c), and t_(d), and assuming ideal losslessconditions at these planes, the X-cube defines a set of input-outputrelations as

I_(AO)=I_(AI)(1−t_(a))(1−t_(d))+I_(BI)t_(a)(1−t_(d))+I_(CI)t_(c)t_(d)+I_(DI)(1−t_(c))t_(d)

I_(BO)=I_(AI)t_(a)(1−t_(b))+I_(BI)(1−t_(a))(1−t_(b))+I_(cI)(1−t_(c))t_(b)+I_(DI)t_(c)t_(b)

I_(CO)=I_(AI)t_(a)t_(b)+I_(BI)(1−t_(a))t_(b)+I_(CI)(1−t_(c))(1−t_(b))+I_(DI)t_(c)(1−t_(b))

I_(DO)=I_(AI)(1−t_(a))t_(d)+I_(BI)t_(a)t_(d)+I_(CI)t_(c)(1−t_(d))+I_(DI)(1−t_(c))(1−t_(d))

Thus, depending upon the choice of transmission coefficients, the fouroutputs can be used for various applications. Table 1 summarizes threepossible applications for the X-cube.

First, in the first line of Table 1, the X-cube functions as a lossless4×4 beam-splitter or star-coupler by selecting all four transmissioncoefficients to be 0.5. In this case, each of the four outputs receivesa quarter of its optical power from all four inputs. For awavelength-division multiplexer (WDM) star-coupling application, abroadband coating on each of the four filter sections to cover and passthe four wavelength channels is essential.

The second application, shown in the second through fifth lines in Table1, is a passive wavelength router where each of the four inputs containsfour identical wavelength channels [Y. Tachikawa, and M. Kawachi,“Lightwave transrouter based on array-waveguide grating multiplexer,”Electron. Lett., (1994) 1504-1506]. The purpose of a WDM wavelengthrouter is to permute among wavelength-and-space coded channels. As shownin the left column of Table 1, each of the four reflective planes servesto transmit two adjacent wavelength bands while reflecting the other twowavelength bands (in the second line, t_(a) has transmission coefficientof 1 for λ₁ and λ₂ and has a transmission coefficient of 0 for λ₃ andλ₄). When the four planes are coated accordingly, each of the fouroutput space channels shuffles their wavelength channels in the waysummarized in the middle column in Table 1.

The third possible application presented in the bottom lines of Table 1is a two channel WDM add/drop multiplexer which can download datatransmitted by two wavelength carriers, say λ_(i) and λ_(j) out of npossible WDM channels (λ_(I), λ_(i), . . . , λ_(j), . . . λ_(n)), and atthe same time upload new data to the two wavelength carriers [K.-P. Hoand S.-V. Liaw, “Eight-channel bidirectional WDM add/drop multiplexer,”Electron. Lett., (1998) 947-948]. In this case, only six out of theeight ports of the X-cube are used, two for the main input and outputchannels, and two each for the added/dropped wavelength channels foreach carrier. The corresponding filter assignments are given in Table 1.In addition to the mentioned applications, other possible embodimentscan include applications with polarization-coded beam-splitting andfiltering. Moreover other embodiments can employ active filter planesincorporating switching functionalities, whereby additional applicationsand uses of the 4×4 solid optical component are possible.

To facilitate the usage of the X-cube, precision fabrication andintegration of individual components must be executed. In oneembodiment, to fabricate a fiber-interfaced 4×4 star-coupler, a set offour high precision right-angle roof-top prisms of 35 mm base length wasselected to have a 6 second angular tolerance for the 90° angle, and a15 second tolerance for the two other angles. The surface flatness ofall three optical planes of the prism was controlled to be within oneoptical fringe defined by using interferometric methods. These prismswere then coated with multilayer dielectric coatings designed for 50/50splitting ratio for the λ=1300 nm for one of their two roof-planes, withanti-reflection coatings for their base-plane. The other roof-plane wasnot coated in order for the cemented X-cube to be 50% reflective at allfour of its internal planes. The cementing process did not use anyactive alignment method. The four individual prisms were cemented in twosteps, first to form two 2-prism pairs and second to cement the twocomposite units together. The first step was executed when the twoprisms were placed on a piece of flat glass with a second referenceperpendicular glass plate placed as a reference adjacent to the combinedprism's vertical plane. The second and final step was performed withonly one reference plane, the bottom glass plate. The fabricated X-cubewas intended for a fiber-optics interface. To facilitate theopto-mechanical packaging, eight interfacing multimode fiber collimatorswere acquired and tested. These collimators were capable of beingconfigured as collimating-focusing pairs. The insertion loss for such apair was designed to be 0.8 dB. Four such collimating-focusing pairswere tested for their actual insertion losses vs. the free-space gapdistance between the collimator and focuser. FIG. 2(a), shows the testscan results indicating a reasonable uniformity around 0.87 dB for a gapdistance as large as 120 mm. When the gap distance was fixed at 60 mm(the designed gap distance when considering the prism media's refractiveindex), each pair was also tested for its lateral misalignment tolerance(see FIG. 2(b) for a typical scan) and angular misalignment tolerance(see FIG. 2(c) for a typical scan).

An opto-mechanical packaging of the fiber-interfaced X-cube module wasdesigned accordingly. The main housing has a raised floor to place theX-cube, four walls, each having two round holes to insert the fibercollimators, illustrated schematically in phantom at 20 in FIG. 1. Thetop cap of the housing contains four adjusting screws for minor twodimensional (2D) tilt adjustment of the already placed X-cube. Each ofthe eight fiber-collimators was fixed into a triangularly shapedspring-loaded mounting block. Each such block was designed to be twodimensional (2D) angularly adjustable. Because the collimating-focusingpairs have 3 dB lateral displacement tolerance in the order of hundredsof microns, the entire opto-mechanical mounting did not incorporateseparate displacement adjustment capability, as the precision of partsfabrication and X-cube placement should be well within the allowedtolerance range. To analyze the overall tolerances of the entirepackaging, the emphasis was on angular tolerance induced errors. Thesources of such errors come from both the X-cube's angular errors θ_(ip)and θ_(op) (each beam can be reflected twice at most) and thefiber-collimator's alignment errors α_(ip) and α_(ip) respectively. Thesubscripts ip and op denote in-plane and out-of-plane components withrespect to the plane referred to as the beam propagation plane. Theerrors can affect outputs in the form of both displacement errors:Δ_(ip) and Δ_(op) and angular errors: Δβ_(ip) and Δβ_(op). A summary ofthe tolerance analysis in a truth table format is shown in Table 2 whered denotes the gap distance between two end surfaces of the fibercollimating-focusing pair. As shown in the last row of the table, themost damaging case happens when all four errors are present.

For the final integration and packaging, four fiber polarizationcontrollers were used before input fibers to filter outpolarization-related errors from the power meters. Alignment was startedby activating input IA, and aligning all four outputs. Activation ofinputs I_(CI), I_(BI), and I_(DI) was in order. Each time, re-adjustmentof alignments was needed. It was noticed that inclusions of the firstthree inputs were relatively easy. The last input was most difficult todeal with. With the inclusion of the polarization controller and X-cube,the average total insertion loss increased by about 1.23 dB to 2.1 dB.The splitting ratios of the packaged X-cube device were measured asfollows. To filter out the error caused by the insertion loss, we letthe measured splitting ratio S be$S = \frac{I_{iO}}{I_{AO} + I_{BO} + I_{CO} + I_{DO}}$

for all four inputs, i.e. I_(AI), I_(BI), I_(CI), and I_(DI), where i=A,B, C, D. Each of the sixteen measured data was then divided by thedesigned X-cube splitting ratio to yield the uniformity measure U whichshould be unity in an ideal situation. The average of sixteen data:U_(AV) and its variance au were obtained for two sets of measurements.Before the final alignment, U_(AV)=1.002 and σ_(U)=0.104. After thefinal alignment, they became U_(AV)=1.036 and σ_(U)=0.279, respectively.For both situations, s-polarization state was used for all four inputs.Excluding the surrounding fiber polarization controllers, dimensions ofthe X-cube opto-mechanical packaging was 70×70×30 mm³.

To summarize, the present invention has demonstrated a new solid-opticscomponent, an X-cube composite prism which has 4×4 input/outputchannels. The X-cube can be used for beam-splitting, star-coupling, VDMwavelength routing, and add/drop multiplexing, among many other passiveand active operations. An X-cube-based and fiber-interfacedopto-mechanical packaging module was designed and implemented, and itsperformance showed a 2.1 dB insertion loss, a uniformity ratio of 1.036and a uniformity variance of 0.279.

t_(ai) = t_(bj) = t_(ci) = t_(dj) = 1.0 all other t_(a,b,c,d) = 0 suchthat, I_(AI) = I(λ_(I) . . . λ_(i drop), . . . λ_(j drop), . . . λ_(n))I_(BI) = I(λ_(i add)), I_(DI) = 0, I_(DI) = I(λ_(j add)) I_(AO) =I(λ_(I) . . . λ_(i add), . . . λ_(j add), . . . λ_(n)) I_(BO) =I(λ_(i drop)), I_(CO) = 0, I_(DO) = I(λ_(j drop)).

TABLE 2 Summary Tolerance due to Angular Alignment Errors Prism InputOutput Alignment Error θ_(ip) θ_(op) α_(ip) α_(op) Δ_(ip) Δ_(op) Δβ_(ip)Δβ_(ip) 0 0 0 0 0 0 0 0 0 0 0 α_(op) 0 dα_(op) 0 α_(op) 0 0 α_(ip) 0dα_(ip) 0 0 0 0 0 α_(ip) α_(op) dα_(ip) dα_(op) 0 α_(op) 0 θ_(op) 0 0 0dθ_(op) 0 θ_(op) 0 θ_(op) 0 α_(op) 0 d(θ_(op) + α_(op)) 0 θ_(op) +α_(op) 0 θ_(op) α_(ip) 0 dα_(ip) dθ_(op) 0 θ_(op) 0 θ_(op) α_(ip) α_(op)dα_(ip) d(θ_(op) + α_(op)) 0 θ_(op) + α_(op) θ_(ip) 0 0 0 dθ_(ip) 0θ_(ip) 0 θ_(ip) 0 0 α_(op) dθ_(ip) dα_(op) θ_(ip) α_(op) θ_(ip) 0 α_(ip)0 d(θ_(ip) + α_(ip)) 0 θ_(ip) + α_(ip) 0 θ_(ip) 0 α_(ip) α_(op)d(θ_(ip) + α_(ip)) dα_(op) θ_(ip) + α_(ip) α_(op) θ_(ip) θ_(op) 0 0dθ_(ip) dθ_(op) θ_(ip) θ_(op) θ_(ip) θ_(op) 0 α_(op) dθ_(ip) d(θ_(op) +α_(op)) θ_(ip) θ_(op) + α_(op) θ_(ip) θ_(op) α_(ip) 0 d(θ_(ip) + α_(ip))dθ_(op) θ_(ip) + α_(ip) θ_(op) θ_(ip) θ_(op) α_(ip) α_(op) d(θ_(ip) +α_(ip)) d(θ_(op) + α_(op)) θ_(ip) + α_(ip) θ_(op) + α_(op)

FIG. 3 illustrates an additional embodiment which adds additional sets(1 to n) of optical channel paths beyond the one set of four primaryoptical channel paths illustrated in FIG. 1. In this embodiment each setof four optical channel paths is positioned at a different fixed andspaced position along the central longitudinal axis (the axis alongwhich the apexes of the four roof-top prisms meet) of the X-cube.

Moreover, in the embodiment of FIG. 3 the X-shaped intersecting internalplanes can be divided into more than four different intensitytransmission coefficients, for instance each different fixed and spacedposition along the axis could have different intensity transmissioncoefficients, for instance each different for each different set.

In FIG. 3 the X-cube is shared by different sets of optical inputs andoutputs spaced along the vertical dimension. In this way, each physicalX-cube block can process many sets of optical inputs and outputs. Byincorporating different transmission coefficients, these sets canperform different optical functions.

FIG. 4 illustrates a further embodiment which also adds additional sets(1 to n) of optical channel paths beyond the one set of four primaryoptical channel paths illustrated in FIG. 1. In this embodiment each setof four optical channel paths is positioned in the same planeperpendicular to the longitudinal axis of the X-cube, but spaced atdifferent distances from the longitudinal axis of the X-cube. Theoptical channel paths designated as set 1 are positioned a fixeddistance from the longitudinal axis along the intersecting internalplanes while the optical channel paths designated as set n arepositioned a larger fixed distance from the longitudinal axis along theintersecting internal planes. The concept of FIG. 4 can be extended toany number n of optical channel paths, each positioned as a differentfixed and spaced position from the longitudinal axis along theintersecting internal planes.

Moreover, the X-shaped intersecting internal planes can be divided intomore than four different intensity transmission coefficients, forinstance eight different intensity transmission coefficients for theembodiment of FIG. 4, or a greater number for a larger number n.

In the embodiment of FIG. 4 different sets of optical inputs/outputs areshared laterally within the same cross-section plane of the X-cube.

Moreover, the concepts of the embodiments of FIGS. 3 and 4 could becombined to have n sets, each of which is spaced at different positionsalong the longitudinal axis (FIG. 3), and each of which is furthermultiplied into n further sets, each of which is spaced a differentdistance along the intersecting internal planes from the longitudinalaxis. Moreover, the number of different intensity transmissioncoefficients could be increased in accordance therewith.

While several embodiments and variations of the present invention for anX-cube integrated solid optical component are described in detailherein, it should be apparent that the disclosure and teachings of thepresent invention will suggest many alternative designs to those skilledin the art.

What is claimed is:
 1. An integrated solid optical module for opticalbeam splitting and/or optical filtering, comprising an assembly of fourright-angle roof-top prisms positioned with the apex of each roof-topprism at the center of the assembly, such that the assembly defines twomutually orthogonal and intersecting internal planes which intersect atthe center of assembly, to form four sections of the intersectinginternal planes which form up to four or more primary optical channelpaths having up to four or more potential inputs I_(AI), I_(BI), I_(CI)and I_(DI), and four or more potential outputs I_(AO), I_(BO), I_(CO)and I_(DO) and wherein the outputs depend upon functionalities providedby the four sections of the intersecting internal planes, and whereindenoting intensity transmission coefficients of the four sections of theintersecting internal planes as t_(a), t_(b), t_(c), and t_(d) andassuming ideal lossless conditions at the intersecting internal planes,the integrated solid optical module defines the following set ofinput-output relations,I_(AO)=I_(AI)(1−t_(a))(1−t_(d))+I_(BI)t_(a)(1−t_(d))+I_(CI)t_(c)t_(d)+I_(DI)(1−t_(c))t_(d)I_(BO)=I_(AI)t_(a)(1−t_(b))+I_(BI)(1−t_(a))(1−t_(b))+I_(cI)(1−t_(c))t_(b)+I_(DI)t_(c)t_(b)I_(CO)=I_(AI)t_(a)t_(b)+I_(BI)(1−t_(a))t_(b)+I_(CI)(1−t_(c))(1−t_(b))+I_(DI)t_(c)(1−t_(b))I_(DO)=I_(AI)(1−t_(a))t_(d)+I_(BI)t_(a)t_(d)+I_(CI)t_(c)(1−t_(d))+I_(DI)(1−t_(c))(1−t_(d)),and depending upon the transmission coefficients, the optical module andfour outputs are used for different applications.
 2. An integrated solidoptical module in claim 1, comprising a 4×4 beam splitter orstar-coupler wherein all four transmission coefficients aresubstantially 0.5 and each of the four outputs receives a quarter of itsoptical power from each of the four inputs.
 3. An integrated solidoptical module as claimed in claim 2, comprising a wavelength -divisionmultiplexer (WDM) star-coupler wherein a broadband filter coating isapplied to each of the four sections, to pass four wavelengths of lightin the four optical channels.
 4. An integrated solid optical module asclaimed in claim 1, comprising a 16×16 channel wavelength-divisionmultiplexer (WDM) passive wavelength router each of the four inputscontains four identical wavelength channels and wherein the WDM passivewavelength router permutes among wavelength-and-space coded channels,and wherein t_(a)(λ₁,λ₂)=1, t_(a)(λ₃,λ₄)=0 t_(b)(λ₂,λ₃)=1,t_(b)(λ₁,λ₄)=0 t_(c)(λ₃,λ₄)=1, t_(c)(λ₁,λ₂)=0 t_(d)(λ₁,λ₄)=1,t_(d)(λ₂,λ₃)=0, such that each of the four sections transmits twowavelength bands and reflects two other wavelength bands, and each ofthe four channels outputs are shuffled as followsI_(AO)=I_(AI)(λ₃)+I_(BI)(λ₂)+I_(CI)(λ₄)+I_(DI)(λ₁)I_(BO)=I_(AI)(λ₁)+I_(BI)(λ₄)+I_(CI)(λ₂)+I_(DI)(λ₃)I_(CO)=I_(AI)(λ₂)+I_(BI)(λ₃)+I_(CI)(λ₁)+I_(DI)(λ₄)I_(DO)=I_(AI)(λ₄)+I_(BI)(λ₁)+I_(CI)(λ₃)+I_(DI)(λ₂).
 5. An integratedsolid optical module as claimed in claim 1, comprising a two channeladd/drop wavelength-division multiplexer (WDM) which downloads datatransmitted by any two wavelength carriers out of n possible WDMchannels and uploads new data to the two wavelength carriers, such thatonly six out of the eight channels of the integrated solid opticalmodule are used, two for the main input and the output channels, and twoeach for the added/dropped wavelength channels for each carrier, and thecorresponding filter assignments are t_(ai)=t_(bj)=t_(ci)=t_(dj)=1.0 allother t_(a,b,c,d)=0 such that, I_(AI)=I(λ₁ . . . λ_(l drop), . . .λ_(j)drop, . . . , λ_(n)) I_(BI)=I(λ_(i add)), I_(CI)=0,I_(DI)=I(λ_(j add)) I_(AO)=I(λ₁ . . . λ_(i add), . . . λ_(j add), . . .λ_(n)) I_(BO)=I(λ_(i drop)), I_(CO)=0, I_(DO)=I(λ_(j drop)).
 6. Anintegrated solid optical module as claimed in claim 1, further includingpolarization-coded beam-splitting and/or filtering.
 7. An integratedsolid optical module as claimed in claim 1, wherein the four filterplane sections incorporate active switching functionalities.
 8. Anintegrated solid optical module as claimed in claim 1, furthercomprising a fiber-optics interface, which includes eight interfacingmultimode fiber collimators configured as four collimating-focusingfiber pairs.
 9. An integrated solid optical module as claimed in claim1, including at least one additional set (1 to n) of optical channelpaths in addition to the set of four primary optical channel paths,wherein each additional set of four optical channel paths is positionedat a different fixed and spaced position along the central axis at whichthe apexes of the four roof-top prisms meet.
 10. An integrated solidoptical module as claimed in claim 9, including at least one additionalset (1 to n) of optical channel paths in addition to the set of fourprimary optical channel paths, wherein each additional set of fouroptical channel paths is positioned in the same plane perpendicular tothe central axis of the optical module as the four primary opticalchannel paths, but spaced at a different distance from the central axisof the optical module.
 11. An integrated solid optical module as claimedin claim 1, including at least one additional set (1 to n) of opticalchannel paths in addition to the sets of four primary optical channelpaths, wherein each additional set of four optical channel paths ispositioned in the same plane perpendicular to the central axis of theoptical module as the four primary optical channel paths, but spaced ata different distance from the central axis of the optical module.